Functional organic particle, and method for preparing the same

ABSTRACT

The present invention relates to functional organic particles having functional nanoparticles dispersed in an organic polymeric matrix, wherein the distribution of the functional nanoparticles is increased in the direction toward increasing the particle diameter from the center of the functional organic particles, and to a method for preparing the same.

TECHNICAL FIELD

The present invention relates to functional organic particles, and amethod for preparing the same. More specifically, the present inventionrelates to functional organic particles having functional nanoparticlesdispersed in an organic polymeric matrix, which exhibit excellentfunctionality even with the use of a small amount of functionalnanoparticles, and to a method for preparing the same.

The present application claims the benefit of Korean Patent ApplicationNo. 2005-0046706 (filed on Jun. 1, 2005), which is incorporated hereinby its entirety for reference.

BACKGROUND ART

Conductive organic particles, as an example of the functional organicparticles, have conventionally been prepared by a method comprisingspreading a metal such as platinum on the surface of the fine organicparticles synthesized by emulsion polymerization or dispersionpolymerization in a post-treatment process. This conventional method hasan advantage that a uniform and thin conductive film can be formed onthe surface of the fine organic particle. However, it has disadvantagesthat it is difficult to select a polymerizable or spreadable rawmaterial for, and the cost of the spreadable raw materials is high, thusit being difficult to provide massive production thereof.

In order to overcome the disadvantages, Korean Patent Laid-openpublication No. 2003-0049007 describes a method which comprises mixing anano-sized silver colloidal solution, a monomer, an emulsifier, aninitiator, and the like, and then subjecting the mixture to emulsionpolymerization, dispersion polymerization, microemulsion polymerization,or the like, so as to capsule the silver particles with a resincomposition.

However, the capsule prepared by this method has the silver particlesirregularly dispersed in the inside of the polymeric resin, and thus thesilver particles deeply embedded in the polymeric resin do not playtheir roles. therefore, the fact that a large amount of the silverparticles should be added to obtain a sufficient effect poses a problem.

[Disclosure]

[Technical Problem]

The present inventors found a structure of the functional organicparticles which can exhibit excellent functionality even with the use ofa small amount of functional nanoparticles. Further, the presentinventors found a method for preparing the functional organic particleshaving such structure so that it have a uniform conformation and anarrow particle diameter distribution. Therefore, it is an object of thepresent invention to provide functional organic particles having suchstructure and a method for preparing the same.

[Technical Solution]

The present invention provides functional organic particles comprisingan organic polymeric matrix, and functional nanoparticles dispersed inthe organic polymeric matrix, wherein the distribution amount of thefunctional nanoparticles is increased in the direction toward increasingthe particle diameter from the center, in order to accomplish the abovedescribed objects.

Further, the present invention provides a method for preparing thefunctional organic particles comprising an organic polymeric matrix, andfunctional nanoparticles dispersed in the organic polymeric matrix,which comprises a step of preparing a mixture of the monomers by mixinga monomer, a molecular weight modifier and the functional nanoparticles;a first reaction step of adding a polymerization initiator to themixture of the monomers and reacting said mixture; and a second reactionstep of mixing a product from the first reaction with a dispersantsolution, and reacting said product by applying a centrifugal forcerequired so as to increase the distribution amount of the functionalnanoparticles in the direction toward increasing the particle diameterfrom the center of the functional organic particles.

The method for preparing the functional organic particles can furthercomprise, after the second reaction step, a third reaction step ofapplying, to the product from the second reaction, a centrifugal forceweaker than that applied in the second reaction step.

The present invention will be described in detail below.

FIG. 1 is a cross-sectional view illustrating an example of thefunctional organic particles of the present invention. It should benoted that the present invention is not limited to the functionalorganic particles as configured in FIG. 1. Referring to FIG. 1, thefunctional organic particles (10) of the present invention comprise anorganic polymeric matrix (11), and the functional nanoparticles (12)dispersed in the organic polymeric matrix, wherein the distributionamount of the functional nanoparticles (12) is increased in thedirection toward increasing the particle diameter from the center of thefunctional organic particles (10).

In the case where the content of the functional nanoparticles isincreased in the direction toward increasing the particle diameter fromthe center of the functional organic particles, the distribution amountof the functional nanoparticles positioned adjacent to the surface areincreased, and thus the availability of the functional nanoparticles isincreased. Accordingly, even with the use of a small amount of thefunctional nanoparticles, functional organic particles exhibitingrelatively excellent functionality can be provided.

The monomer constituting the organic polymeric matrix contained in thefunctional organic particles is not particularly limited, but preferredis a monomer having at least one vinyl group. Specifically, i) at leastone aromatic vinyl-based monomer selected from the group consisting ofstyrene, monochlorostyrene, methylstyrene and dimethylstyrene, ii) atleast one acrylate-based monomer selected from the group consisting ofmethyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate,dodecyl acrylate and 2-ethylhexyl acrylate, iii) at least onemethacrylate-based monomer selected from the group consisting of methylmethacrylate, ethyl methacrylate, n-butyl methacrylate, isobutylmethacrylate, dodecyl methacrylate and 2-ethylhexyl methacrylate, andiv) at least one a diene-based monomer selected from the groupconsisting of butadiene and isoprene can be used.

Further, the organic polymeric matrix is preferably polymerized with theaddition of at least one crosslinking agent selected from the groupconsisting of divinylbenzene, ethylene dimethacrylate, ethylene glycoldimethacrylate, diethylene glycol diacrylate, 1,6-hexamethylenediacrylate, allyl methacrylate, 1,1,1-trimethylolpropane triacrylate,triallylamine and tetraallyloxyethane, to the monomers. The crosslinkingagent can improve the mechanical strength of the functional organicparticles.

The functional nanoparticles dispersed in the organic polymeric matrixare not limited in the functions and the kinds of the materials, as longas they impart the intended functions to the organic particle containingthe same. In the present invention, the functional nanoparticles may be,for example, conductive nanoparticles, colored nanoparticles, chargecontrol agents nanoparticles, or the like. In the case where the chargecontrol agents are used as the nanoparticles having high frictionelectrification properties, it is possible to prepare antistaticfunctional organic particles.

The conductive nanoparticles may consist of a) at least one functionalmetal selected from the group consisting of copper, silver, gold,platinum, indium tin oxide (ITO) and antimony tin oxide (ATO), b) atleast one nanocarbon selected from the group consisting of carbon black,graphite, carbon nanotube, fullerene, carbon nanohorn, carbon nanoringand carbon nanowire, or c) a mixture comprising at least two of them.

The functional nanoparticles are preferably contained in an amount of0.1 to 50% by weight, relative to the total weight of the functionalorganic particles.

If the content of the functional nanoparticles is less than 0.1% byweights, the functional organic particles cannot exhibit sufficientfunctionality, while if the content of the functional nanoparticles ismore than 50% by weight, it is difficult to form the structure of thefunctional organic particles of the present invention.

The functional organic particles of the present invention preferably hasa particle diameter of 100 nm to 1 mm, and more preferably a particlediameter of 0.5 to 100 μm. If the particle diameter of the functionalorganic particles is less than 100 nm, it is not easy to handle it,while if the particle diameter of the functional organic particles ismore than 1 mm, the spacing between the functional nanoparticles becomeslarger, and thus the functional organic particles may not sufficientlyexhibit the functionality imparted by the functional nanoparticles.

Further, the functional nanoparticles contained in the functionalorganic particles preferably has a particle diameter of 10 nm to 100 μm,and more preferably a particle diameter of 10 nm to 1 μm. If theparticle diameter of the functional nanoparticles is less than 10 nm, itis difficult for the functional nanoparticles to constitute a specificdistribution, while if the particle diameter of the functionalnanoparticles is more than 100 μm, it is difficult to form the structureof functional organic particles of the present invention.

However, for the purpose of allowing the functional nanoparticles tohave a desired distribution in the present invention, the particlediameter of the functional nanoparticles is preferably ¼ or less of theparticle diameter of the functional organic particles, within the aboverange of the particle diameters.

Particularly, in the functional organic particles, 70% to 100% of thetotal number of the functional nanoparticles are preferably contained inthe outer region up to the point corresponding to 50% of the radius ofthe functional organic particle in the direction from the surface to thecenter of functional organic particle. If the number of the functionalnanoparticles contained in the outer region is less than 70% of thetotal numbers, it isdifficult to attain thestability of thenanoparticles, and the effect of improving the functionality in thefunctional organic particles is insignificant.

FIG. 2 is a cross-sectional view illustrating an example of thefunctional organic particles, in which 70% to 100% of the total numberof the functional nanoparticles (12) are contained in the outer region(24) up to the point (23) corresponding to 50% of the radius of thefunctional organic particle in the direction from the surface to thecenter of the functional organic particle. It should be noted that thepresent invention is not limited to the functional organic particles asconfigured in FIG. 2.

Further, the functional organic particles of the present inventionfurther preferably have a thickness of the functionalnanoparticles-concentrated layer comprising 70% to 100% of the totalnumber of the functional nanoparticles in the outer region (24), of 10nm or more. If the thickness of the functionalnanoparticles-concentrated layer is less than 10 nm, the structure ofthe organic particles may be corrupted while using the functionalorganic particles, and if the functional nanoparticles are theconductive nanoparticles, there is a fear that the transfer of theconductivity of the functional organic particles is blocked.

FIG. 3 is a cross-sectional view illustrating an example of thefunctional organic particles (30), in which the thickness of the region(33) comprising 70% to 100% of the total number of the functionalnanoparticles (12) in the outer region (24) is 20 nm. It should be notedthat the present invention is not limited to the functional organicparticles as configured in FIG. 3.

Further, the functional organic particles of the present invention canfurther comprise a stabilizer for the functional nanoparticles, whichare added so as to concentrate the functional nanoparticles around thesurface of the functional organic particles. The stabilizer for thefunctional nanoparticles is preferably a polymeric material which is notsensitive to the temperatures or the acids. Specifically, it is morepreferably at least one selected from the group consisting of linearester-based polymers, styrene-based polymers and acrylate-basedpolymers, and most preferably at least one selected from the groupconsisting of styrene-butadiene-styrene, styrene-isoprene-styrene,styrene-ethylene-butylene-styrene, andstyrene-ethylene-propylene-styrene block copolymers.

In order to provide the functional nanoparticles contained in thefunctional organic particles with a specific structure of the presentinvention, in the method for preparing the functional organic particles,it is preferable to apply a centrifugal force during the suspensionpolymerization.

Further, in order to exhibit the effect by applying the centrifugalforce, the functional nanoparticles preferably have a higher specificdensity than that of the organic polymeric matrix. If the specificdensity of the functional nanoparticles is not higher than that of theorganic polymeric matrix, the structure of the functional organicparticles is not formed by the centrifugal force, and the distributionof the functional nanoparticles must depend only on a thermodynamicmethod. therefore, it is difficult to concentrate the functionalnanoparticles around the surface of the functional organic particles.

The functional organic particles of the present invention can beprepared by a method for preparing the functional organic particles,which comprises a step of preparing a mixture of the monomers by mixinga monomer, a molecular weight modifier, and the functionalnanoparticles; a first reaction step of adding a polymerizationinitiator to the mixture of the monomers and reacting said mixture; anda second reaction step of mixing a product from the first reaction witha dispersant solution, and reacting said product by applying acentrifugal force required so as to increase the distribution amount ofthe functional nanoparticles in the direction toward increasing theparticle diameter from the center of the functional organic particles.

The method for preparing the functional organic particles can furthercomprise, after the second reaction step, a third reaction step ofapplying a centrifugal force, to the product from the second reaction,weaker than that applied in the second reaction step.

The dispersant solution refers to a solution having a dispersant in aninert solvent. Non-limiting examples of the inert solvent include water.

As the molecular weight modifier, preferred is at least one selectedfrom the group consisting of t-dodecyl mercaptan, n-dodecyl mercaptan,n-octyl mercaptan, carbon tetrachloride and carbon tetrabromide.

In the step of preparing a mixture of the monomers, a stabilizer forfunctional nanoparticles can be further added. Further, in the step ofpreparing the mixture of the monomers, a crosslinking agent can befurther added. In the method for preparing the functional organicparticles, the monomers, the stabilizer for the functionalnanoparticles, the functional nanoparticles, and the crosslinking agentare the same as defined above, thus detailed description thereof beingomitted.

The mixture of the monomers are preferably prepared by mixing 0.001 to 8parts by weight of a molecular weight modifier, and 0.1 to 50 parts byweight of the functional nanoparticles, and optionally preferably 0.1 to50 parts by weight of a stabilizer for the functional nanoparticles,relative to 100 parts by weight of the monomers. If the composition ofthe mixture of the monomers are not within the above range, it isdifficult to form the structure of the functional organic particles ofthe present invention.

The method of preparing the mixture of the monomers is not particularlylimited, but it preferably involves mixing the components at normaltemperature at a rotation speed of 500 to 3000 rpm for 30 minutes to5hours, and more preferably mixing the monomers using a bead mill.

As the polymerization initiator which is added to the mixture of themonomers, a conventional polymerization initiator can be used.Specifically, an addition polymerization initiator can be used, andexamples thereof include an azo-based initiator, an organicperoxide-based initiator, or persulfate, and preferably at least onepolymerization initiator selected from the group consisting ofazobisisobutyronitrile, azobisvaleronitrile, benzoyl peroxide, lauroylperoxide, potassium persulfate, and ammonium persulfate.

The content of the polymerization initiator is not particularly limited,because it can be selectively used within the range of the content usedin a conventional polymerization reaction. In the case of additionpolymerization, preferably 0.01 to 5 parts by weight, and morepreferably 0.1 to 2 parts by weight of the polymerization initiator isused, relative to 100 parts by weight of the monomers. If the content ofthe polymerization initiator is less than 0.01 parts by weight, thereaction proceeds slowly, and thus it is impossible to obtain a desiredreaction yield. Further, if the content of the polymerization initiatoris more than 5 parts by weight, the dispersity of the functionalnanoparticles is lowered, and thus it is impossible to preparepreferable functional organic particles.

In the first reaction, the reaction is preferably performed understirring at 30 to 95° C. for 1 to 30 minutes. If the temperature in thefirst reaction is lower than 30° C., or the reaction time for the firstreaction is shorter than 1 minute, and thus sufficient initiation by thepolymerization initiator does not occur. Further, if the temperature inthe first reaction is higher than 90° C., or the reaction time for thefirst reaction is longer than 30 minutes, the viscosity of the reactantincreases due to excessive reaction, and thus it is difficult touniformly form particles.

Apart from the first reaction, a dispersant solution maintained at 30 to95° C. is prepared. In order to avoid the drastic change in thetemperature of the product of the first reaction, the temperature of thedispersant solution is more preferably maintained at the sametemperature as that of the product of the first reaction.

In the second reaction step, the product of the first reaction is addedto the dispersant solution and react there. Here, the dispersant is usedfor optimization of the particle diameter distribution of the functionalorganic particles. Examples of the dispersant preferably include a) atleast one inorganic dispersant selected from the group consisting ofsilica, an insoluble calcium salt and an insoluble magnesium salt, b) atleast one anionic surfactant selected from the group consisting of afatty acid salt, an alkyl sulfuric acid ester salt, analkylaryl sulfuricacidester salt, dialkyl sulfosuccinate and alkyl phosphate, or c) atleast one nonionic surfactant selected from the group consisting ofpolyoxyethylene alkyl ether, polyoxyalkylene alkylphenol ether, sorbitanfatty acid ester, polyoxyalkylene fatty acid ester, glycerin fatty acidester, polyvinyl alcohol, alkyl cellulose, and polyvinylpyrrolidone, andmore preferably colloidal silica, calcium phosphate, magnesiumhydroxide, or polyvinyl alcohol.

The inert solvent in the dispersant solution is preferably water, and inthis case, the concentration of the dispersant in the aqueous dispersantsolution is not particularly limited, but it is preferably 0.1 to 50parts by weight, relative to 100 parts by weight of water. If thecontent of the dispersant is less than 0.1 parts by weight, the effectof dispersant is insignificant. Further, the content of the dispersantis more than 50 parts by weight, due to the side reaction of emulsionpolymerization, the particles containing no functional nanoparticles aregenerated, and thus the functional organic particles are not uniformlyformed.

The second reaction step is preferably performed by mixing the productof the first reaction:the dispersant solution at a weight ratio of 1:95to 50:50. If the weight ratio of the product of the first reaction:thedispersant solution is less than 1:95, the dispersion effect isremarkable, but the final amount of the functional organic particles tobe produced is insignificant, and thus commercial production thereof isdifficult. Further, if the weight ratio of the product of the firstreaction:the dispersant solution is more than 50:50, the dispersionstability is hardly accomplished, and thus large particles maybe formedduring the polymerization reaction.

The second reaction step is preferably performed at 30 to 95° C. for 5to 60 minutes. If the temperature of the second reaction is lower than30° C., sufficient initiation of the polymerization initiator does notoccur, and thus it is insufficient for the reaction to be proceeded.Further, if the reaction time is less than 5 minutes, the effect time ofthe centrifugal force to the particles is not sufficient, and thus it isinsufficient for the desired particle structure, and the particlediameter of the functional organic particles is not uniform due torelatively short effect time of shear force. If the temperature in thesecond reaction is higher than 95° C. or the reaction time for thesecond reaction is longer than 60 minutes, excessive reaction occurs,thus leading to a fear of agglomeration of the reactants.

Further, in the second reaction step, a centrifugal force required so asto increase the distribution amount of the functional nanoparticles inthe direction toward increasing the particle diameter from the center ofthe functional organic particles is preferably applied to the reactants.The centrifugal force can be applied using a common stirrer or ahomogenizer, and preferably a homogenizer in the second reaction step.

The centrifugal force required so as to increase the distribution amountof the functional nanoparticles in the direction toward increasing theparticle diameter from the center of the functional organic particlesvaries depending on the particle diameter and the distribution ofdesired functional organic particles, and preferably it is in the rangeof approximately 50 G to 5000 G. If the centrifugal force is less than50 G, the functional nanoparticles are not distributed outwardly fromthe functional organic particles, while if the centrifugal force is morethan 5000 G, the structure of the functional organic particles may becorrupted due to excessive centrifugal force.

The centrifugal force applied in the second reaction step are dividedinto a centrifugal force applied by a rotation speed of the rotor of astirrer, particularly a homogenizer (revolutional centrifugal force),and a centrifugal force in the inside of the particle by the rotation ofthe particles generated by the shear force applied to the functionalorganic particles (rotational centrifugal force). These two types of thecentrifugal force act in combination, so as to allow the functionalnanoparticles to be positioned in the surface direction thereof.

In the third reaction step, it is preferable that the reactioncontinuously proceeds at 30 to 95° C. for 5 to 30 hours, and preferably5 to 15 hours. Further, in the third reaction step, it is preferable toapply a smaller centrifugal force than that in the second reaction step.For example, in the range of 1 G to 1000 G, a smaller centrifugal forcethan that in the second reaction step is preferred. In this case, in thesimilar way to the second reaction step, a revolutional centrifugalforce and a rotational centrifugal force act on these functional organicparticles.

There occurs a phenomenon that the functional nanoparticles areconcentrated on the surface of the functional organic particles due tothe centrifugal force usually at an initial stage in the reaction. Ifthe polymerization reaction proceeds to a certain degree, the viscosityof the organic polymeric matrix increases, and thus the speed of theconcentration of the functional nanoparticles on the surface thereof isdrastically lowered.

Accordingly, in order to prepare effective functional organic particles,design of a stabilizer for the functional nanoparticles, and regulationof the centrifugal force and the reaction rate with a stirrer should beappropriately combined.

After completion of the third reaction step, if desired, apost-treatment step may be performed so as to remove the dispersantadded in the reaction process and the agglomerates generated in thereaction step.

The method for removing the dispersant in the post-treatment step is notparticularly limited, but in the case of colloidal silica, a method inwhich an aqueous sodium hydroxide solution is added to the functionalorganic particle suspension obtained after completion of the thirdreaction step, so as to adjust the concentration of sodium hydroxide to0.05 to 0.2 N, can be used.

Further, the agglomerates produced in the above-described reaction stepcan be screened using a sieve. The mesh of the sieve can be arbitrarilyselected according to a desired size of the functional organicparticles.

The product of the third reaction having the dispersant and theagglomerates removed, the product of the third reaction can be furthersubjected to a centrifugal seperation-decantation-redispersion process,during which the remaining dispersant and the reaction by-products canbe removed.

The product of the third reaction, from which the dispersant and thereaction by-products were removed, is further filtered to removemoisture, and dried to obtain final functional organic particles. FIG. 4illustrates a TEM photograph of a cross-section of the functionalorganic particles having the functional nanoparticles distributed on thesurface.

Hereinbelow, preferred examples of the present invention will bedescribed. The following examples are only for the illustrative purpose,not limiting the scope of the present invention.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating an example of thefunctional organic particles of the present invention.

FIG. 2 is a cross-sectional view illustrating of an example of thefunctional organic particles, in which 70% to 100% of the total numberof the functional nanoparticles are contained in the outer region up tothe point corresponding to 50% of the radius of the functional organicparticle in the direction from the surface to the center of functionalorganic particle.

FIG. 3 is a cross-sectional view illustrating an example of thefunctional organic particles, in which the thickness of the regioncomprising 70% to 100% of the total number of the functionalnanoparticles in the outer region is 20 nm.

FIG. 4 is a view illustrating a photograph of a cross-section of thefunctional organic particles having the functional nanoparticlesdistributed on the surface.

BEST MODE EXAMPLE 1

(Preparation of Powders of Functional Organic Particles)

In a reactor with an inner volume of 500 ml, 10 g of colloidal silica asa dispersant was melted in 400 g of distilled water, and the reactiontemperature was raised to 70° C., which is a reaction temperature, toprepare a dispersant solution.

Separately, 160 g of styrene, 40 g of butyl acrylate, 4 g of allylmethacrylate as a cross linking agent, and 0.02 g of n-dodecyl mercaptanas a molecular weight modifier were added and mixed, and 3.5 g of astyrene-butadiene-styrene block copolymer as a stabilizer for thefunctional nanoparticles, having a styrene content of 30% by weight anda weight average molecular weight of 70,000 g/mole was sufficientlymelted into the mixture. To the mixture, 10 g of indium tin oxide (ITO)having an mean particle diameter of 50 nm was added, the resultant wasstirred at 2000 rpm for 2 hours using a bead mill, and then the beadswere removed, thereby obtaining 105 g of a mixture of the monomers.

The mixture of the monomers was put into a water bath at 70° C. toelevate the temperature thereof, 2 g of azobisisobutyronitrile as apolymerization initiator was added thereto, and the mixture was stirredfor 5 minutes to perform a first reaction.

The product of the first reaction was mixed with the previously prepareddispersant solution, and the mixture was stirred using a homogenizer ata centrifugal force of 2000 G at 70° C. for 20 minutes to perform asecond reaction.

The product of the second reaction was subject to the third reaction byapplying a centrifugal force of 15 G using a common stirrer at 70° C.for 15 hours to prepare functional organic particles.

(Post-Treatment)

Thus prepared functional organic particles were present in thesuspension form, to which an aqueous sodium hydroxide solution was addedto adjust the concentration of sodium hydroxide to 0.1 N, and thussilica as a dispersant was removed from the surface of the functionalorganic particles.

After the above-described process, the resultant was sieved with a150-mesh sieve to remove the agglomerates and then dried.

The product of the third reaction, which had remained after drying, wassubject to repetition of the processes of centrifugalseperation-decantation-redispersion, to remove the dispersant and thereaction by-products. Further, the remaining product was filtered toremove moisture, and thus the remaining cake of the functional organicparticles was dried under vacuum at normal temperature for 48 hours, toprepare powders of the functional organic particles.

EXAMPLE 2

(Preparation of Powders of Functional Organic Particles)

In a reactor with an inner volume of 500 ml, 10 g of colloidal silica asa dispersant was melted in 400 g of distilled water, and the reactiontemperature was raised to 70° C., which is a reaction temperature, toprepare a dispersant solution.

Separately, 160 g of styrene, 40 g of butyl acrylate, 4 g of allylmethacrylate as a cross linking agent, and 0.02 g of n-dodecyl mercaptanas a molecular weight modifier were added and mixed, and 3.5 g of astyrene-butadiene-styrene block copolymer as a stabilizer for thefunctional nanoparticles, having a styrene content of 30% by weight anda weight average molecular weight of 70,000 g/mole was sufficientlymelted into the mixture. To the mixture, 2 g of carbon black FW200(Degussa) having an mean particle diameter of 13 nm was added, theresultant was stirred at 2000 rpm for 2 hours using a bead mill, andthen the beads were removed, thereby obtaining 105 g of a mixture of themonomers.

The mixture of the monomers was put into a water bath at 70° C. toelevate the temperature thereof, 2 g of azobisisobutyronitrile as apolymerization initiator was added thereto, and the mixture was stirredfor 5 minutes to perform a first reaction.

The product of the first reaction was mixed with the previously prepareddispersant solution, and the mixture was stirred using a homogenizer ata centrifugal force of 2000 G at 70° C. for 20 minutes to perform asecond reaction.

Using a common stirrer, the product of the second reaction was subjectto the third reaction by applying a centrifugal force of 15 G at 70° C.for 15 hours to prepare functional organic particles.

(Post-Treatment)

Thus prepared functional organic particles were present in thesuspension form, to which an aqueous sodium hydroxide solution was addedto adjust the concentration of sodium hydroxide to 0.1 N, and thussilica as a dispersant was removed from the surface of the functionalorganic particles.

After the above-described process, the resultant was sieved with a150-mesh sieve to remove the agglomerates and then dried.

The product of the third reaction, which had remained after drying, wassubject to repetition of the processes of centrifugalseperation-decantation-redispersion, to remove the dispersant and thereaction by-products. Further, the remaining product was filtered toremove moisture, and thus the remaining cake of the functional organicparticles was dried under vacuum at normal temperature for 48 hours, toprepare powders of the functional organic particles.

EXAMPLE 3

(Preparation of Powders of Functional Organic Particles)

In a reactor with an inner volume of 500 ml, 10 g of colloidal silica asa dispersant was melted in 400 g of distilled water, and the reactiontemperature was raised to 70° C., which is a reaction temperature, toprepare a dispersant solution.

Separately, 160 g of styrene, 40 g of butyl acrylate, 4 g of allylmethacrylate as a cross linking agent, and 0.02 g of n-dodecyl mercaptanas a molecular weight modifier were added and mixed, and 3.5 g of astyrene-butadiene-styrene block copolymer as a stabilizer for thefunctional nanoparticles, having a styrene content of 30% by weight anda weight average molecular weight of 70,000 g/mole was sufficientlymelted into the mixture. To the mixture, 20 g of indium tin oxide (ITO)having an mean particle diameter of 50 nm was added, the resultant wasstirred at 2000 rpm for 2 hours using a bead mill, and then the beadswere removed, to prepare 105 g of a mixture of the monomers.

The mixture of the monomers was put into a water bath at 70° C. toelevate the temperature thereof, 2 g of azobisisobutyronitrile as apolymerization initiator was added thereto, and the mixture was stirredfor 5 minutes to perform a first reaction.

The product of the first reaction was mixed with the previously prepareddispersant solution, and the mixture was stirred using a common stirrerat a centrifugal force of 50 G at 70° C. for 20 minutes to perform asecond reaction.

The product of the second reaction was subject to the third reaction byapplying a centrifugal force of 40 G using the common stirrer at 70° C.for 15 hours to prepare functional organic particles.

(Post-Treatment)

Thus prepared functional organic particles were present in thesuspension form, to which an aqueous sodium hydroxide solution was addedto adjust the concentration of sodium hydroxide to 0.1 N, and thussilica as a dispersant was removed from the surface of the functionalorganic particles.

After the above-described process, the resultant was sieved with a150-mesh sieve to remove the agglomerates and then dried.

The product of the third reaction, which had remained after drying, wassubject to repetition of the processes of centrifugalseperation-decantation-redispersion, to remove the dispersant and thereaction by-products. Further, the remaining product was filtered toremove moisture, and thus the remaining cake of the functional organicparticles was dried under vacuum at normal temperature for 48 hours, toprepare powders of the functional organic particles.

EXAMPLE 4

Powders of the functional organic particles were prepared in the samemanner as in Example 1, except that 3.5 g of astyrene-ethylene-butylene-styrene (SEBS) copolymer as a stabilizer forthe functional nanoparticles, and 10 g of carbon nanotubes as thefunctional nanoparticles were used.

COMPARATIVE EXAMPLE 1

(Preparation of Powders of Functional Organic Particles)

In a reactor with an inner volume of 500 ml, 10 g of colloidal silica asa dispersant was melted in 400 g of distilled water, and the reactiontemperature was raised to 70° C., which is a reaction temperature, toprepare a dispersant solution.

Separately, 160 g of styrene, 40 g of butyl acrylate, 4g of allylmethacrylate as a cross linking agent, and 0.02 g of n-dodecyl mercaptanas a molecular weight modifier were added and mixed, and 3.5 g of astyrene-butadiene-styrene block copolymer as a stabilizer for thefunctional nanoparticles, having a styrene content of 30% by weight anda weight average molecular weight of 70,000 g/mole was sufficientlymelted into the mixture. To the mixture, 0.1 g of carbon black having anmean particle diameter of 12 nm was added, the resultant was stirred at2000 rpm for 2 hours using a bead mill, and then the beads were removed,thereby preparing 105 g of a mixture of the monomers.

The mixture of the monomers was put into a water bath at 70° C. toelevate the temperature thereof, 2 g of azobisisobutyronitrile as apolymerization initiator was added thereto, and the mixture was stirredfor 5 minutes to perform a first reaction.

The product of the first reaction was mixed with the previously prepareddispersant solution, and the mixture was stirred using a homogenizer ata centrifugal force of 4000 G at 70° C. for 20 minutes to perform asecond reaction.

The product of the second reaction was subject to the third reaction byapplying a centrifugal force of 15 G using a common stirrer at 70° C.for 15 hours to prepare functional organic particles.

(Post-Treatment)

Thus prepared functional organic particles were present in thesuspension form, to which an aqueous sodium hydroxide solution was addedto adjust the concentration of sodium hydroxide to 0.1 N, and thussilica as a dispersant was removed from the surface of the functionalorganic particles.

After the above-described process, the resultant was sieved with a150-mesh sieve to remove the agglomerates and then dried.

The product of the third reaction, which had remained after drying, wassubject to repetition of the processes of centrifugalseperation-decantation-redispersion, to remove the dispersant and thereaction by-products. Further, the remaining product was filtered toremove moisture, and thus the remaining cake of the functional organicparticles was dried under vacuum at normal temperature for 48 hours, toprepare powders of the functional organic particles.

COMPARATIVE EXAMPLE 2

(Preparation of Powders of Functional Organic Particles)

In a reactor with an inner volume of 500 ml, 10 g of colloidal silica asa dispersant was melted in 400 g of distilled water, and the reactiontemperature was raised to 70° C., which is a reaction temperature, toprepare a dispersant solution.

Separately, 160 g of styrene, 40 g of butyl acrylate, 4 g of allylmethacrylate as a cross linking agent, and 0.02 g of n-dodecyl mercaptanas a molecular weight modifier were added and mixed, and 3.5 g of astyrene-butadiene-styrene block copolymer as a stabilizer for thefunctional nanoparticles, having a styrene content of 30% by weight anda weight average molecular weight of 70,000 g/mole was sufficientlymelted into the mixture. To the mixture, 100 g of indium tin oxide (ITO)having an mean particle diameter of 50 nm was added, the resultant wasstirred at 2000 rpm for 2 hours using a bead mill, and then the beadswere removed, to prepare 105 g of a mixture of the monomers.

The mixture of the monomers was put into a water bath at 70° C. toelevate the temperature thereof, 2 g of azobisisobutyronitrile as apolymerization initiator was added thereto, and the mixture was stirredfor 5 minutes to perform a first reaction.

The product of the first reaction was mixed with the previously prepareddispersant solution, and the mixture was stirred using a common stirrerat a centrifugal force of 10 G at 70° C. for 20 minutes to perform asecond reaction.

The product of the second reaction was subject to the third reaction byapplying a centrifugal force of 1 G using a common stirrer at 70° C for15 hours to prepare functional organic particles.

(Post-Treatment)

Thus prepared functional organic particles were present in thesuspension form, to which an aqueous sodium hydroxide solution was addedto adjust the concentration of sodium hydroxide to 0.1 N, and thussilica as a dispersant was removed from the surface of the functionalorganic particles.

After the above-described process, the resultant was sieved with a150-mesh sieve to remove the agglomerates and then dried.

The product of the third reaction, which had remained after drying, wassubject to repetition of the processes of centrifugalseperation-decantation-redispersion, to remove the dispersant and thereaction by-products. Further, the remaining product was filtered toremove moisture, and thus the remaining cake of the functional organicparticles was dried under vacuum at normal temperature for 48 hours, toprepare powders of the functional organic particles.

COMPARATIVE EXAMPLE 3

(Preparation of Powders of Functional Organic Particles)

In a reactor with an inner volume of 500 ml, 10 g of colloidal silica asa dispersant was melted in 400 g of distilled water, and the reactiontemperature was raised to 70° C., which is a reaction temperature, toprepare a dispersant solution.

Separately, 160 g of styrene, 40 g of butyl acrylate, 4 g of allylmethacrylate as a cross linking agent, and 0.02 g of n-dodecyl mercaptanas a molecular weight modifier were added and mixed, and 3.5 g of astyrene-butadiene-styrene block copolymer as a stabilizer for thefunctional nanoparticles, having a styrene content of 30% by weight anda weight average molecular weight of 70,000 g/mole was sufficientlymelted into the mixture. To the mixture, 5 g of carbon black having anmean particle diameter of 12 nm was added, the resultant was stirred at2000 rpm for 2 hours using a bead mill, and then the beads were removed,to prepare 105 g of a mixture of the monomers.

The mixture of the monomers was put into a water bath at 70° C. toelevate the temperature thereof, 2 g of azobisisobutyronitrile as apolymerization initiator was added thereto, and the mixture was stirredfor 5 minutes to perform a first reaction.

The product of the first reaction was mixed with the previously prepareddispersant solution, and the mixture was stirred using a common stirrerat a centrifugal force of 10 G at 70° C. for 20 minutes to perform asecond reaction.

The product of the second reaction was subject to the third reaction byapplying a centrifugal force of 1 G using a common stirrer at 70° C. for15 hours to prepare functional organic particles.

(Post-Treatment)

Thus prepared functional organic particles were present in thesuspension form, to which an aqueous sodium hydroxide solution was addedto adjust the concentration of sodium hydroxide to 0.1 N, and thussilica as a dispersant was removed from the surface of the functionalorganic particles.

After the above-described process, the resultant was sieved with a150-mesh sieve to remove the agglomerates and then dried.

The product of the third reaction, which had remained after drying, wassubject to repetition of the processes of centrifugalseperation-decantation-redispersion, to remove the dispersant and thereaction by-products. Further, the remaining product was filtered toremove moisture, and thus the remaining cake of the functional organicparticles was dried under vacuum at normal temperature for 48 hours, toprepare powders of the functional organic particles.

COMPARATIVE EXAMPLE 4

(Preparation of powders of Organic Particles)

In a reactor with an inner volume of 500 ml, 10 g of colloidal silica asa dispersant was melted in 400 g of distilled water, and the reactiontemperature was raised to 70° C., which is a reaction temperature, toprepare a dispersant solution.

Separately, 160 g of styrene, 40 g of butyl acrylate, 4 g of allylmethacrylate as a crosslinking agent, and 0.02 g of n-dodecyl mercaptanas a molecular weight modifier were added and mixed, and 3.5 g of astyrene-butadiene-styrene block copolymer having a styrene content of30% by weight and a weight average molecular weight of 70,000 g/mole wassufficiently melted into the mixture. The resultant was stirred at 2000rpm for 2 hours using a bead mill, and then the beads were removed, toprepare 105 g of a mixture of the monomers.

The mixture of the monomers was put into a water bath at 70° C. toelevate the temperature thereof, 2 g of azobisisobutyronitrile as apolymerization initiator was added thereto, and the mixture was stirredfor 5 minutes to perform a first reaction.

The product of the first reaction was mixed with the previously prepareddispersant solution, and the mixture was stirred using a homogenizer ata centrifugal force of 2000 G at 70° C. for 20 minutes to perform asecond reaction.

The product of the second reaction was subject to the third reaction byapplying a centrifugal force of 15 G using a common stirrer at 70° C.for 15 hours to prepare organic particles.

(Post-Treatment)

Thus prepared organic particles were present in the suspension form, towhich an aqueous sodium hydroxide solution was added to adjust theconcentration of sodium hydroxide to 0.1 N, and thus silica as adispersant was removed from the surface of the organic particles.

After the above-described process, the resultant was sieved with a150-mesh sieve to remove the agglomerates and then dried.

The product of the third reaction, which had remained after drying, wassubject to repetition of the processes of centrifugalseperation-decantation-redispersion, to remove the dispersant and thereaction by-products. Further, the remaining product was filtered toremove moisture, and thus remaining cake of the organic particles wasdried under vacuum at normal temperature for 48 hours, to preparepowders of the organic particles. Platinum was deposited on the surfaceof the organic particles to obtain organic particles having a thicknessof the platinum layer of 0.1 μm.

Various physical properties of the functional organic particles preparedaccording to Examples 1 to 4 and Comparative Examples 1 to 4 wasmeasured in the following manner, and the results are shown in thefollowing Table 1.

Mean particle diameter and particle diameter distribution

Using a multisizer coulter counter, a mean volume diameter was measured,and using SEM, the particle diameter and the particle diameterdistribution were measured. In the following Table 1, the particlediameter distribution indicates a standard deviation of the particlediameter.

Distribution of functional nanoparticles

Using TEM, the distribution of the functional nanoparticles wasmeasured.

Electric conductivity

Using an equipment for measuring the resistance of the powders, thevolume resistance was measured, thus giving measurements of the electricconductivity of the functional organic particles. TABLE 1 mean particleDistribution amount (%) Amount of particle diameter of functionalElectric agglomerates diameter distribution nanoparticles containedConductivity relative to solids (μm) (μm) in the outer region (S/cm) (%by weight) Ex. 1 7.2 1.8 85 3.7 × 10⁻⁵ 1.2 Ex. 2 7.6 1.7 90 4.3 × 10⁻⁵2.3 Ex. 3 98 20 75 2.1 × 10⁻⁴ 12.3 Ex. 4 6.9 1.5 95 4.3 × 10⁻⁴ 0.6 Comp.Ex. 1 0.12 0.02 45 2.1 × 10⁻⁶ 3.4 Comp. Ex. 2 102 21 42 2.6 × 10⁻⁷ 15.3Comp. Ex. 3 7.6 2.0 21 3.4 × 10⁻⁷ 2.1 Comp. Ex. 4 7.6 1.6 — 2.0 × 10⁻⁵3.0

The outer region refers to a region up to the point corresponding to 50%of the radius of the functional organic particle in the direction fromthe surface to the center of functional organic particle.

As shown in the above Table 1, the functional organic particles of thepresent invention exhibit uniform particle diameter distribution andexcellent electric conductivity.

INDUSTRIAL APPLICABILITY

The functional organic particles of the present invention can exhibitrelatively excellent functionality even with the use of a small amountof the functional nanoparticles. In the present invention, if conductivenanoparticles are used as the functional nanoparticles, it is possibleto easily improve the functionalities of shielding micro wavelength asactive ingredients of plastics for shielding micro wavelength, orcoating compositions for shielding micro wavelength, and they can bealso used as a laser printer developer which allows a high resolutionpattern to be formed, instead of a toner.

1. Functional organic particles comprising an organic polymeric matrix,and functional nanoparticles dispersed in the organic polymeric matrix,wherein the distribution amount of the functional nanoparticles isincreased in the direction toward increasing the particle diameter fromthe center of the functional organic particles.
 2. The functionalorganic particles according to claim 1, wherein the functional organicparticles have a particle diameter of 100 nm to 1 mm, the functionalnanoparticles have a particle diameter of 10 nm to 100 μm, and theparticle diameter of the functional nanoparticles is ¼ or less of theparticle diameter of the functional organic particles.
 3. The functionalorganic particles according to claim 1, wherein the content of thefunctional nanoparticles is 0.1 to 50% by weight, relative to the totalweight of the functional organic particles.
 4. The functional organicparticles according to claim 1, wherein 70% to 100% of the total numberof the functional nanoparticles are contained in the outer region up tothe point corresponding to 50% of the radius of the functional organicparticle in the direction from the surface to the center of functionalorganic particle.
 5. The functional organic particles according to claim1, wherein the thickness of the outer region comprising 70% to 100% ofthe number of the functional nanoparticles is 10 En or more from thesurface of the functional organic particle.
 6. The functional organicparticles according to claim 1, wherein the functional nanoparticleshave higher specific densities than those of the organic polymericmatrix.
 7. The functional organic particles according to claim 1,wherein the functional nanoparticles are conductive nanoparticles,colored nanoparticles or charge control agents nanoparticles.
 8. Thefunctional organic particles according to claim 7, wherein theconductive nanoparticles consist of a) at least one functional metalselected from the group consisting of copper, silver, gold, platinum,indium tin oxide (ITO) and antimony tin oxide (ATO), b) at least onenanocarbon selected from the group consisting of carbon black, graphite,carbon nanotube, fullerene, carbon nanohorn, carbon nanoring and carbonnanowire, or c) a mixture comprising at least two of them.
 9. Thefunctional organic particles according to claim 1, wherein the organicpolymeric matrix is polymerized with at least one monomer selected fromthe group consisting of: i) at least one aromatic vinyl-based monomerselected from the group consisting of styrene, monochlorostyrene,methylstyrene and dimethylstyrene; ii) at least one acrylate-basedmonomer selected from the group consisting of methyl acrylate, ethylacrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate and2-ethylhexyl acrylate; iii) at least one methacrylate-based monomerselected from the group consisting of methyl methacrylate, ethylmethacrylate, n-butyl methacrylate, isobutyl methacrylate, dodecylmethacrylate and 2-ethylhexyl methacrylate; and iv) at least one adiene-based monomer selected from the group consisting of butadiene andisoprene.
 10. The functional organic particles according to claim 1,wherein the organic polymeric matrix is polymerized with the addition ofat least one crosslinking agent selected from the group consisting ofdivinylbenzene, ethylene dimethacrylate, ethylene glycol dimethacrylate,diethylene glycol diacrylate, 1,6-hexamethylene diacrylate, allylmethacrylate, 1,1,1-trimethylolpropane triacrylate, triallylamine andtetraallyloxyethane, to the monomers.
 11. The functional organicparticles according to claim 1, wherein the functional organic particlesfurther comprise a stabilizer for the functional nanoparticles.
 12. Thefunctional organic particles according to claim 11, wherein thestabilizer for the functional nanoparticles is at least one selectedfrom the group consisting of linear ester-based polymers, styrene-basedpolymers and acrylate-based polymers.
 13. The functional organicparticles according to claim 1, wherein the functional organic particlesare prepared by applying a centrifugal force in a suspensionpolymerization.
 14. A method for preparing the functional organicparticles comprising an organic polymeric matrix, and functionalnanoparticles dispersed in the organic polymeric matrix, whichcomprises: a) a step of preparing a mixture of the monomers by mixing amonomer, a molecular weight modifier, and the functional nanoparticles;b) a first reaction step of adding a polymerization initiator to themixture of the monomers and reacting said mixture; and c) a secondreaction step of mixing a product from the first reaction with adispersant solution, and reacting said product by applying a centrifugalforce required so as to increase the distribution amount of thefunctional nanoparticles in the direction toward increasing the particlediameter from the center of the functional organic particles.
 15. Themethod for preparing the functional organic particles according to claim14, further comprising, after the c) step, d) a third reaction step ofapplying, to the product from the second reaction, a centrifugal forceweaker than that applied in the second reaction step.
 16. The method forpreparing the functional organic particles according to claim 14,wherein the monomer in the a) step is at least one selected from thegroup consisting of: i) at least one aromatic vinyl-based monomerselected from the group consisting of styrene, monochlorostyrene,methylstyrene and dimethylstyrene; ii) at least one acrylate-basedmonomer selected from the group consisting of methyl acrylate, ethylacrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate and2-ethylhexyl acrylate; iii) at least one methacrylate-based monomerselected from the group consisting of methyl methacrylate, ethylmethacrylate, n-butyl methacrylate, isobutyl methacrylate, dodecylmethacrylate and 2-ethylhexyl methacrylate; and iv) at least one adiene-based monomer selected from the group consisting of butadiene andisoprene.
 17. The method for preparing the functional organic particlesaccording to claim 14, wherein the polymerization is performed with theaddition of at least one crosslinking agent selected from the groupconsisting of divinylbenzene, ethylene dimethacrylate, ethylene glycoldimethacrylate, diethylene glycol diacrylate, 1,6-hexamethylenediacrylate, allyl methacrylate, 1,1,1-trimethylolpropane triacrylate,triallylamine and tetraallyloxyethane in the a) step.
 18. The method forpreparing the functional organic particles according to claim 14,wherein the molecular weight modifier in the a) step is at least oneselected from the group consisting of t-dodecyl mercaptan, n-dodecylmercaptan, n-octyl mercaptan, carbon tetrachloride and carbontetrabromide.
 19. The method for preparing the functional organicparticles according to claim 14, wherein in a) step, a stabilizer forthe functional nanoparticles is further added.
 20. The method forpreparing the functional organic particles according to claim 14,wherein the mixture of the monomers in the a) step are prepared bymixing 0.001 to 8 parts by weight of a molecular weight modifier, and0.1 to 50 parts by weight of the functional nanoparticles, and 0.01 to50 parts by weight of the polymerization initiator in the b) step isused, relative to 100 parts by weight of the monomers.
 21. The methodfor preparing the functional organic particles according to claim 14,wherein the dispersant in the c) step includes at least one dispersantselected from: i) at least one inorganic dispersant selected from thegroup consisting of silica, an insoluble calcium salt and an insolublemagnesium salt; ii) at least one anionic surfactant selected from thegroup consisting of a fatty acid salt, an alkyl sulfuric acid estersalt, an alkylaryl sulfuric acid ester salt, dialkyl sulfosuccinate andalkyl phosphate; or iii) at least one nonionic surfactant selected fromthe group consisting of polyoxyethylene alkyl ether, polyoxyalkylenealkylphenol ether, sorbitan fatty acid ester, polyoxyalkylene fatty acidester, glycerin fatty acid ester, polyvinyl alcohol, alkyl cellulose,and polyvinylpyrrolidone.
 22. The method for preparing the functionalorganic particles according to claim 14, wherein inert solvent in thedispersant solution in the c) step is water, and dispersant in theaqueous dispersant solution is contained in a proportion of 0.1 to 50parts by weight, relative to 100 parts by weight of water.
 23. Themethod for preparing the functional organic particles according to claim22, wherein in the c) step, the weight ratio of the product of the firstreaction and the dispersant solution is 1:95 to 50:50.
 24. The methodfor preparing the functional organic particles according to claim 14,wherein the centrifugal force applied in the c) step is 50 to 5000 G.25. The method for preparing the functional organic particles accordingto claim 15, wherein the centrifugal force applied in the d) step is 1to 1000 G.
 26. The method for preparing the functional organic particlesaccording to claim 14, wherein in the b) step, the reaction ispreferably performed under stirring at 30 to 95° C. for 1 to 30 minutes,and in the c) step, and the reaction is performed under application of50 to 5000 G of a centrifugal force by stirring at 30 to 95° C. for 5 to60 minutes.
 27. The method for preparing the functional organicparticles according to claim 15, wherein in the d) step, and thereaction is performed under application of 1 G to 1000 G of acentrifugal force by stirring at 30 to 95° C. for 5 to 30 hours.
 28. Themethod for preparing the functional organic particles according to claim14, wherein the functional organic particles have a particle diameter of100 nm to 1 mm, the functional nanoparticles have a particle diameter of10 nm to 100 μm, and the particle diameter of the functionalnanoparticles is ¼ or less of the particle diameter of the functionalorganic particles.
 29. The method for preparing the functional organicparticles according to claim 14, wherein the functional nanoparticlesare used in an amount of 0.1 to 50% by weight, relative to the totalweight of the functional organic particles, in the functional organicparticles.
 30. The method for preparing the functional organic particlesaccording to claim 14, wherein the functional nanoparticles have higherspecific densities than those of the organic polymeric matrix.
 31. Themethod for preparing the functional organic particles according to claim14, wherein the functional nanoparticles are conductive nanoparticles,colored nanoparticles or charge control agents nanoparticles.
 32. Themethod for preparing the functional organic particles according to claim14, wherein, after the c) step, a step of removing the dispersant,reaction agglomerates and reaction by-products, are further carried out.33. The method for preparing the functional organic particles accordingto claim 15, wherein, after the d) step, a step of removing thedispersant, reaction agglomerates and reaction by-products, is furthercarried out.
 34. The method for preparing the functional organicparticles according to claim 14, wherein, after the c) step, a step offiltering to remove moisture and drying is further carried out.
 35. Themethod for preparing the functional organic particles according to claim15, wherein, after the d) step, a step of filtering to remove moistureand drying is further carried out.